Beta-Lactams Flashcards
Beta-lactam drugs
Penicillins
Cephalosporins
Carbapenems
Monobactams
What is essential about the structure of beta-lactams?
Beta-lactam ring
General classifications of Penicillins
Natural: Penicillin G
Amino: Ampicillin, Amoxicillin
Anti-Staphylococcal: Oxacillin
Entended Spectrum: Piperacillin
Beta-lactam MOA
Prevention of cell wall formation and lysis of bacterial cells
-Bactericidal for growing cells
Dosing for Beta-lactams
Time dependent
Lower dose, more frequently
Paradoxical effect for beta-lactams
Concentrations above optimal killing conc result in reduced bactericidal effect due to growth arrest: need a growing cell to kill
Resistance to beta-lactams
Beta-lactamase enzymes produced by bacteria
-Need to add beta-lactamase inhibitory drugs
Beta-lactamase inhibitors
A way to block resistance via beta-lactamase enzymes
Clavulanic acid
Avibactam
Tazobactam
Commonly mixed w/ beta lactams
PK properties of penicillins
Poor oral absorption
Short half-life/rapid elimination
Small vol of distribution
Renal elimination
Penicillin G
Mostly active against gram + aerobes and anaerobes, less activity against staph, gram -, and E coli
Hypersensitivity rx most common side effect
What species are susceptible to procain tox?
Birds
Snakes
Turtles
Guinea Pigs
Chinchillas
What is the drug of choice for mixed aerobic-anaerobic infections, such as cat bites?
Ampicillin or amoxicillin
What is the drug of choice for treating UTIs and lepto?
Amoxicillin
Which penicillin is inherently more resistant to beta-lactamase enzymes?
Cephalosporins
How does activity change as cephalosporins increase in generation?
As generation increases (1 to 4) the gram - coverage increases, but at the cost of gram + coverage
What is ceftiofur used for?
Resp disease of cattle, sheep, swine and horses
UTIs in dogs
How is Convenia/Cefovecin used?
3rd generation Cephalosporin used in dogs and cats. Long lasting treatment, one injection remains above MIC level for 14 days for staph.
What is concerning about the use of cephalosporins?
3 and 4 gen should not be used as first line. Narrowest spectrum should be chosen first.
Convenia is used often just because it is easy.
What does Imipenem do?
Carbapenem: widest activity of any antibiotic
Always administered with cilastatin to prevent nephrotoxicity
Should not be used as first line to prevent resistance
